“People should be on the lookout for water with a green ‘pea soup’ appearance or which contains green, blue, white, red, or brown scums that may be foamy or in mats or blobs,” said Gina LaLiberte, a DNR aquatic research scientist.

Blue-green algae, also known as cyanobacteria, is naturally present in Wisconsin lakes, streams and ponds, according to the DNR. Usually between July and September, when there is a lot of sunlight and high temperatures, the algae are prone to bloom on water surfaces.

"We're seeing more than average, I guess, for this time of year," said Chuck Warzecha the Wisconsin Public Health bureau director. "And, we're expecting even more because it's fairly early in the season."

LaLiberte said if people have any doubts about the appearance of water, stay out of it and consider taking steps to make sure children do not swim or drink water that’s affected.

The most common symptoms of blue-green algae poisoning in humans are rashes, gastrointestinal pain and respiratory irritation, according to Mark Werner, a toxicologist with the Department of Health Services.

The worst cases could cause liver and nervous system problems.

The DNR is also warning people to protect their pets.

“Animals have a higher risk from dying after exposure to blue-green algae toxins because they may ingest large amounts of toxins from drinking lake, pond, or river water or licking algae from their fur,” said DNR veterinarian Lindsey Long.

Signs of blue-green algae poisoning in dogs include loss of appetite, abnormal sluggishness, vomiting and even seizures, she added.